Gyroscopic instrument



May 23, 1944. RASPET 2,349,758

GYROSCOPIC INSTRUMENT Original Filed March 17, 1941 2 Sheets-Sheet 1 INVENTOR. 0405 7 fifispzr ATTORNEYS May 23, 1944. RASPET 2,349,758

GXROSCdPIC INSTRUMENT Original Filed March 17, 1941 2 Sheets-Sheet 2- BY ZI/LQU Q A Patented May 23, 1944 GYROSGOPIC INSTRUMENT August Raspet, Old Lyme, Conn.

Original application March 17, 1941, Serial No.

383,761. Divided and this application November 1'7, 1942, Serial No. 465,932

13 Claims.

This invention relates to improvements in gyroscopic instruments and aims to provide a delicate and accurate gyroscopic instrument which may be manufactured at small cost.

ObJects'of my invention are to provide a gyroscopic instrument whose response is independent of the speed of rotation of the gyroscope rotor, and whose rotor is automatically self-dynamic-balancing.

In a preferred embodiment of my invention I attain these and other objects by utilizing centrifugal force developed by the rotation of the gyroscope rotor to oppose precession of the 83'- roscope and by providing an electrical indicator actuated by a magnetic element on the rotor of the gyroscope. The response of the indicator to precession is directly proportional to the speed of the rotor, and the precessing torque is also directly proportional to the speed of the rotor, so that if precession were opposed by a constant force the response of the indicator would vary directly as the square of the speed of the rotor. But, since precession is opposed by centrifugal force which varies directly as the square of the speed of the rotor, the effect of variations in rotor speed is balanced out so that the actual response of the indicator is independent of variations in the rotor speed.

The nature of this and other features of my invention may best be understood from a detailed description of the specific embodiments of my invention which are shown in the accompanying drawings in which Fig. 1 shows a gyroscopic turn indicator sectioned on a vertical plane containing the axis of the rotor of the gyroscope;

Fig. 2 is a bottom plan view with the box removed showing some parts sectioned on the axis of the rotor;

Fig. 3 is a transverse section taken on the line H of Fig. 1;

Figs. 4, 5, 6 and '7 are fragmentary views of the gyroscope rotor and the connection between it and the support, similar to the left-hand side of Fig. 1, showing modified centrifugal elements;

Fig. 8 is a diagram of the electric circuit of the indicator; and

Fig. 9 shows a modified circuit.

The support of the instrument illustrated consists of a box ill, a cover-l. an open transverse A frame ll secured to the cover, and an open 1ongitudinal frame l2 which is supported at one end by'the frame H and adjustably supported near the other end by a rod 13 depending from the cover.

The rotor-bearing frame l5 of the gyroscope is pivoted on the support. The pivot is formed by a cross-shaft IS on the frame I! ioumalled in ball bearings ll mounted in the transverse frame ll of the support. The frame I! provides bearings It for th shaft 20 of the gyroscope rotor. The frame I5 also carries a weight I9 which is adjusted so as to place the center of gravity of the gyroscope on the axis of the pivot IS. The frame I5 may, if desired, be provided with any usual damping means.

The gyroscope rotor is electrically driven in the form illustrated. Its shaft 20 carries, in addition to the flywheel 2|, an armature 22 and a commutator 23 to which the winding of the armature is connected. The field pieces of the motor consist of permanent magnets 24 formin part of the gyroscope frame l5, and the brushes 25 are also carried by the frame l5 as best seen in Fig. 3.

Centrifugal elements are carried by th gyroscope rotor. In the form shown in Figs. 1 and 2,

they consist of a plurality of slack chains equallyl spaced about the axis of the rotor and extending between the rotor flywheel 2| and a disc 3| anchored to the support by means of a thrust ball bearing 32 secured to the end of the fixed frame I! at a point of the support which lies on a line intersecting the axis of the pivot l5 at right angles. This line is the axis of the gyroscope rotor when the gyroscope is in its normal position. The parts described thus form a connection between the gyroscope and a point of the support which lies on the normal axis of the gyroscope rotor. This connection is tensioned by the centrifugal force of the chains when the rotor is in operation. The tension is, therefore, a direct function of the speed of rotation of the rotor. Since the tension force of the connection between the gyroscope and the support is along a line intersecting the axis of the pivot l6 at right angles, it offers a resistance to precession which is very slight at the beginning of a precession in either direction and which increases rapidly with a continuation of precession in either direction.

The strength of the force resisting the precession, which determines the sensitiveness of the instrument, depends upon the mass and the angle of the chains 30. The sensitiveness of the instrument may be regulated by means of the nut 32' which determines the position of the bearing 32 and the slackness of the chains.

The centrifugal elements 30 have an important function in addition to that of resisting preces- .sion. They serve also to counteract the eflect to move in a gyroscope'rotor, and which, as is well known, automatically flows to the light side of the rotor to balance any eccentricity in the weight of the rotor. I have demonstrated by the actual operation of the device described that the centrifugal elements 3!) reduce the vi bration caused by eccentricity. of the flywheel to a point where it is imperceptible, and thu make the rotor, for all practical purposes, selfdynamic-balancing. This eliminates the large expense ordinarily necessary to produce a perfectly balanced gyroscope flywheel. To accomplish this result, the mass of the chains 30 must be as great as, and preferably considerably greater than, any difl'erence in weight between the two sides of the flywheel. With a flywheel machined with ordinary accuracy, light chains such as those shown in Figs. 1 and 2 are suflicient to effect self-dynamic-balancing as well as to provide a suflicient centralizing force to resist precession.

My invention is not limited to the use of chains as the centrifugal elements and does not require that the centrifugal elements be generally parallel 'to the rotor axis. Thus the chains 30 of Figs. 1 and 2 may be replaced by the centrifugal elements 30a shown in Fig. 4, which consist of flexible wires weighted at their middles and converging toward their point of anchorage to the support. The operation of the centrifugal elements 30a is like that of the chains 30.

My invention may be applied'to produce a gyroscope which isv perfectly self-balancing by placing substantially the entire eflective mass of the gyroscope rotor in outwardly movable centrifugal elements. Such a gyroscope rotor is shown in Fig. which, it will be noted, is similar to the construction shown in Figs. 1, 2, 4, except that the flywheel 2| is replaced by a light disc 2|b and the light centrifugal elements 30 are replaced by massive centrifugal elements 30b.

"This type of gyroscope may be made at small expense, as it is perfectly dynamically-self-balancing and also self-centralizing. By making the heavy centrifugal elements 30b, slacker than the light chains 30 and mounting the disc 3| on a self-aligning bearing 32b, the restoring force produced by the elements 30b may be made approximately the same as the restoring force of the light chains 3|] so that an instrument containing the rotor shown in Fig. 5 may be made as responsive to turns of shown in Fig. 1.

The massive centrifugal connecting elements 30b may take the form of heavy chains, but a feature of my invention consists in reducing air resistance by giving them a stream-lined form such as that shown'in Fig. 5. In this form it will be seen that each element 30b consists of a flexible, inextensible ribbon 33 carrying a stream-lined Weight 38 at its middle rotor shown in Fig. 5 may easily be driven by power applied to either one of the discs 2| b, 3|.

My invention is not limited to the use of centrifugal elements which, like those already described, form part of a connection between the gyroscope and the support. In Fig. 6, the centrifugal elements 300 consist of balls or weights at the ends of'short levers 34 pivoted on the flywheel 200 of the rotor. The levers 34 are in the the support as that point.. The

form of bell cranks connected by linkage", I

to a stub shaft 31 anchored in a thrust ball hearing 32c flxed on the support at the same point as the bearing 32 of Fig. 1. The centrifugal force of the balls tensions the connection between the gyroscope and this point of the support with a force depending upon the speed of rotation of the rotor, so as to produce the same sort of resistance to precession as the centrifugal elements which have been described. While Fig. 6 shows clearances sufficient to permit only a slight precession such as is necessary to operate the elec-- tric indicator hereinafter described, it is apparent that any desired amount of precession may be provided by an increase in the clearances shown.

The centrifugal elements 300 also have the effect of automatically balancing any slighteccentricity in the flywheel, as a ball on the light side of the flywheel will move out further than one on the heavy side.

My invention is not limited to the use of solid centrifugal elements. Fluid centrifugal elements may also be used. In the arrangement shown in Fig. 7, the flywheel 2|d is provided with a plurality of equally spaced radial tubes 39 connecting at their inner ends with a flexible bellows 40 located on the axis of the flywheel. The inner side of the bellows is held in flxed relation to the flywheel by the tubes 39 or other means, and the outer side of the bellows is connected .by a tension member 4| to the stub shaft 3117 anchored in the thrust ball bearing 320 which was described in connection with Fig. 6. The centrlfugal force of a liquid in the tubes tends to draw the liquid out of the bellows 40 and thus produce a tension on the connection 4| whichis dependent upon the rate of rotation of the flywheel so that this device operates in resisting precession in the same way as those which have been described. The liquid centrifugal elements of Fig. 7 also mak the rotor dynamically-selfbalancing regardless of eccentricity in the weight of the flywheel, since the liquid automatically runs out further in the-tube 39 which is at the light side of the wheel until a perfect balance is obtained.

The precession indicator of the instrument is operated by an electric current induced in stationary coils by the magnetic field of a mag-l netic element on the gyroscope rotor. A useful feature of my invention which is, however, not absolutely essential, consists in utilizing the armature of an electric motor driving the rotor as the magnetic element which actuates the electric indicator.

magnitude of the voltage induced in each coil depends upon the distance of its pole piece from the armature. scope precesses so as to move the armature upward, the induced voltage in the coil 53 is higher than that in the coil 54 and the reverse is the case when precession moves the armature downward.

Consequently, when the gyro-' As shown in Fig. 8, the coils II, ll are connected in series in a circuit ll containing two rectiiiers ll, 51. shunted across the circuit 5! from a point between the two rectiflers to a point between the two coils is a circuit 58 containing a center-reading D. C. milliammeter l and a potentiometer "I. When the voltages in the coils 53, N are equal, no current flows through the ammeter, but, when either voltage exceeds the other, a rectified current flows through the ammeter so as to move its pointer in one direction or the other, thus indicating a precession of the gyroscopein one direction or the other due to a turning of the support in one direction or the other. The potentiometer 60 provides means for setting the pointer at its middle or zero position when the gyroscope is in its normal position, even though the voltages in the coils 53, 54 are not exactly equal when the gyroscope is in its normal position. It is, therefore, not essential that the pole pieces 5| be at exactly equal distances from the armature in the normal position of the gyroscope. In the modificat on shown in Fig. 9, the simpl pole pieces 50, ii are replaced by pole pieces Na, Na, each of which consists of two bars ofmagnetic metal connected by a core of magnetic metal which carries a winding. The windings or coils 51a, 53b may be connected in the circuit shown in Fig. 8. In Fig. 9, however, I have shown an alternative, and in some respects preferable, circuit. In this case, the ammeter 59 is connected in the coil circuit 55a and the-rectifiers 56, 51 are shunted across this circuit at opposite sides of the ammeter.

The pole pieces 50, 5| or 50a, 5la are protected from stray magnetic fields bythe box it and cover I. which are made of iron so as to serve as a magnetic shield. This insures accurate operation of the electric indicator, and also prevents the electric motor of the turn indicator from affecting other electrical instruments in its vicnity. I

The ammeter 59 may be placed at any desired distance from the gyroscope. The electric indicator which has been described thus has the advantage of making it unnecessary to place the "gyroscope itself on the instrument board.- The electric indicator is much more sensitive than the mechanical precession indicators used in ordinary gyroscopic instruments. This makes it possible to provide for a much smaller angular movement of the gyroscope frame than that which is required with mechanical indicators, giving the instrument a more accurate and more rapid response to turning movements of the support than can be obtained in instruments using mechanical indicators.

The response of the gyroscopic instrument which has been described is independent of variations of speed of the rotor of the gyroscope. For a given angular turning of the support, the precessing torque, p, is given by the following formula:

where w is the rotational speed of the gyroscope rotor; and the restoring force, r, due to the centrifugal force of the centrifugal elements is given by the following formula:

The response of the pivoted frame of the gyroscope which is caused by the processing torque and resisted by the centrifugal elements is therefore proportional to and is therefore directly proportional to the speed rotation of the rotor.

A decrease in the speed of the rotor increases the response of the pivoted gyroscope frame to a turn of the support in proportion to the change of speed, and at the same time decreases the response of the ammeter in proportion to the change in speed. The two effects therefore balance out, making the response of the ammeter to the turn precisely the same as it was before the decrease in rotational speed occurred. The same balancing out occurs on increases of the rotational speed, so that the response of the indicator is not affected by changes in the speed of the gyroscope rotor. In view of the difficulty of maintaining an absolutely constantspeed of the gyroscope rotor, the instrument gives a uniformity of response to turns not heretofore obtainable.

The self-dynamlc-balancing of the rotors, which has been described, makes it possible to manufacture the instrument which has been described more economically than previously used gyroscopic instruments.

The advantages of my invention to which I have referred are independent of the particular means used for driving the rotor of the gyroscope. Any usual driving means may be substituted for the electric motor shown in the drawings, and the power may be applied to the disc or stub shaft mounted on the support instead of directly to the rotor Journalled on the frame I. Many other changes may be made in this speclfic instrument described and illustrated without departing from my invention.

The present application is a division of my application Serial No. 383,761, filed March 17, 1941.

What I claim is:

1. In a gyroscopic instrument, the combination of a support, a gyroscope having a rotor and a frame pivoted on the support to permit precession of the gyroscope, a centrifugal element carried by the rotor, and means for applying the centrifugal force of said element to resist precession of the gyroscope.

2. In a gyroscopic instrument, the combina- 'tion of a support, a gyroscope having a rotor and a frame pivoted on the support to permit precession of the gyroscope, a centrifugal element carried by the rotor and connected to the support to resist precession of the gyroscope by a force which is a direct function of the speed of the rotor.

3. In a gyroscopic instrument, the combination of a support, a gyroscope having a rotor and a frame pivoted on the support to permit precession of the gyroscope, an anchor iournalled on the support with its axis in line with the axis of the rotor when the gyroscope is in its normal position, a centrifugal element carried by the rotor, and a connection between said element and said anchor to resist precession of the gyroscope by a force which is a direct function of the speed of the rotor.

4. In a gyroscopic instrument, the combinaresists precession of the gyroscope from its nortion of a support, a gyroscope having a rotor and mal position. 7 a. frame pivoted on the support to permit pre- 9. In a gyroscopic instrument, the combinacession of the gyroscope, a plurality of centriftion of a support, a gyroscope having a rotor ugal elements spaced around the rotor and conand a frame pivoted on the support to permit speed of the rotor. actuated by outward movement of the liquid in 5. In a gyroscopic instrument, the combina- 10 the tubes to oppose precession of the gyroscope. tion of a support, a frame pivoted thereon, a ro- 10. In a gyroscopic instrument, the combinaon the support with its axis in line with the axis a frame pivoted on the support to permit preof the first rotor when the frame is in its normal cession of the gyroscope, a plurality of equally position, and a massive, flexible, inextensible, spaced radial tubes on the rotor, a flexible belslack connection between said rotors. lows on the rotor to which the inner ends of said 6. In a. gyroscopic instrument, the combinatubes are connected, and a connection between tion of a support, a frame pivoted on said supsaid bellows and the support to resist precession port, a disc journalled on the frame with its axis of the gyroscope by the centrifugal force of liq transverse to the axis on which the frame is pivuid in the tubes. oted, a disc iournalled on the support with its 11. In a gyroscopic instrument, a self-dynamiaxis in; line with the axis of the first disc when cally-balancing and self-centering gyroscope the frame is in its normal position, a plurality comprising the combination with a support and of massive, flexible, slack connections between a frame pivoted thereo of a pair 01' discs said discs spaced around the discs, and means mounted respectively on the frame and on the for rotating one of the discs. 7 support with their axes in line in the normal po-' 7. In a gyroscopic instrument, a self-dynamisition of the support, a plurality of slack, inexcally-balancing and self-centering gyroscope tensible, flexible ribbons extending between said comprising the combination with a support and discs and stream-lined weights carried by said a frame pivoted thereon, of a pair of discs mountribbons at their middle points, and means for roed respectively on the frame and on the suptatlng one of the discs. port with their axes in line in the normal posi- 12. In a gyroscopic instrument, a self-dynamition of thesupport, a plurality of slack, massive, cally-balancmg and self-centering gyroscope equally spaced around the discs, the mass of said a frame pivoted thereon, of a pair of discs, bear- 8. In a gyroscopic instrument, the combinaflexible connections between said discs, and means tion of a support, a gyroscope having a rotor for rotating one of the discs.

and a frame pivoted on the support to permit 13. In a gyroscopic instrument, the combinaprecession oi' the gyroscope, centrifugal elements tion of a support, a frame pivoted thereon, a disc mounted to the rotor for radially outward movejoumalled on the frame, a self-aligning bearing ment, and a. connection between said elements on the support, a disc journalled on said selfand a point of the support in line with the axis aligning bearing, and massive, flexible, inextentrifugal elements tensions said connections and AUGUST RASPET.

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